High speed dental drill



Aug. 27, 1963 E. HoFFMElsTER HIGH SPEED DENTAL DRILL Filed Aug. 22, 1960 INVENIOR fr/C @ffm/'Sfar FEL BY j //ff ATTORNEY-2S clearance opening disposed between United States Patent 05 3,101,541 HIGH SPEED DENTAL DRILL Erich Hoffmeister, Biberach (Riss), Germany, assignor to Alois Kaltenbach and `Erich Homeister, responsible partners of Kaltenbach and Voight, a kommanditgesellschaft, Biberach (Riss), Germany Filed Aug. 22, 1960, Ser. No. 51,187 Claims priority, application Germany Sept. 7, 1959 8 Claims. (Cl. 32-27) This invention relates to high speed dental drills of the contra-angle type, either-with or without a knee portion, wherein a turbine driven by compressed air is disposed within the head ot"v the contra-angle. The compressed for driving the turbine is introduced through the main body of the handpiece as is also the Water to be supplied to the front `face end of the head and the air exhausted from the turbine is discharged through the `rfront land back ends of the head as Well as through the interior of the handpiece.

In previous instruments of ikind, a disadvantage has been found to exist in that -when the air is exhausted from the rear end of the head in one or more powerful kjets acting in the direction i the turbine rotor axis, it is -annoying to the patient. For example, .if the occlusal surtace .ot a lower posterior tooth being treated, the powerful stream exiting troni the back end of the head is directed against the ,upper teeth and vice versa. This invention effectively eliminates these disadvantages by 4the provision of lone or more holes for the turbine exhaust in the back chamber -wall of the head; these holes being `shielded by ya cap which forms a ring-shaped slot 4opening radially or axially or in both directions t0- wards the exterior which serves to reduce the pressure of the exiting compressed In accordance lwith la' preferred [form yof the invention, the. cap may be iortned integrally with the near chamber wall of the bead. Alternatively, it may also be inserted into the rear chamber wallv or removably attached thereto by a threaded connection'.

Another .feature of the invention consists in the provision of an .opening in the cap in axial alignment with the turbine rotor to provide for the insertion of a tool ejector of a know type.

In order to prevent an excessive :amount of air to escape through the tool ejecting opening in the cap, the clearance between the chamber rwall and the rotating ot .the turbine is reduced to a minimum.

A further characteristic .of the invention consi-sts in the conveying of the turbine exhaust which exits through the front chamber Wall off the bead wthrough an annular the shaft of the turbine rotor and the `front chamber wall of the head. By utilizing this clearance opening, the previously used exhaust openings become superfluous. The cross-sectional area of the annular clearance opening at the yfront end of the head is so dimensioned that the air compressed within the head can escape in equal amounts from the front and rear walls in order to prevent axial displacement of the turbine rotor.

Another feature of the invention is the provision of an annular chamber in the front wall off the head which communicates with Ithe |waterconveying tube and which is provided with one or more openings through the front Wall disposed at an :angle with respect to the axis of the head. In this manner, it is possible to obtain one or more streams of Water lon `the area being treated to provide more uniform and consequently better cooling.

In the drawings; FIG. 1 represents a vertical cross section of one forni of contra-angle head in accordance with the present invention; FIG. 2 is Ia cross-section taken on the line II-IIof FIG. 1; FIG. 3 is a horizontal crosssection .taken on the vline -IIIIII of FIG. l; FIG. 4 is a vertical cross-section of a moditied `form oi contra-angle head; FIG. 5 is a cross-sectional view of another modiication of contra-angle head taken .on the V-V of FIG. 6,`|and; FIG. 6. is aplan view lof .the device shown in FIG. 5.

In the drawings, the casing tor the` head is indicated bythe numeral 1, and disposed therein is a turbine rotor-2. The-shaft 3 ot the rotor is supported in bearings 4 and 5. The rear-chamber wall of the casing 1 is indicated by the numeral 6, while numeral 7 indicates the kfront chamber wall.` As shown in FIG. 3, the compressed is supplied lto the turbine through conduit 8, while the major portion of the exhausted 'air `is carried back through the handpiece through conduit 9'.

In accordance with 'well known practice with devices of lthis type, the compressed air supplied to the turbine rotor 2 yis not completely returned through conduit 9, but a portion of this is used to lubricate the bearings 4 andv S by passing through these bearings and discharging from the front tandrrear, walls off the head respectively. In the drawings, it can be seen that the air conveyed through the rear bearing 5'- enters an enlarged circular chamber 10 from Iwhere itexits through openings 11. The openings 11 in the present invention are of a large enough cross-section so that substantially all of the air passing through the 4rear bearing 5 canA discharge through the openings 1l. v,l

The Aopenings |11 are covered by a disc-shaped cap4 12, the outer edge of'whicli forms a circular slot 13= permitting the air toescape radially outwardly to the atmosphere ,as shown .in FIGS. lthrough 4. By this' arrangement, the pressure of the exhausting Iair is reduced 'and directed laterally in a sufficiently weakened ltorniA so that it is no longer objectionable. y

The cap 12 andthe vrear chamber wall 6 may be formed integrally a's 'is shown in the drawings. cap 12 could be termed separately :and provided with threads yior removable insertion in the wal-l 6.

The inner portion of the cap 12 which may be recessed toreceive the upper endof the rotor shaft 3 is formed so that the clearance, indicated at 14, between the recess and the shaft is reduced to the minimum amount necessary ior free rotation off the shaft so that as little as possible of the :exhaust air will pass through the annular space 14. An opening 15 may .also be provided in .the cap 12 which will permit the introduction ot an ejector tool as is well known in the art.

In IFIGS. l to 3 :as well as 5 .and 6, the chamber wall 6 is Kfastened securely yto the casing 1. `On the other hand, in the modification shown in FIG. 4, the wall 6 is threaded, .as at 16, tor a removable connection with the housing 1.

In the modiiicatio-ns shown in FIGS. 5 and 6, the outer edge of 'the cap 12 is joined to the end 'wall 6 so that no lair escapes in :a radial direction. In this modiiicat-ion, the cap is provided with one or more circular slots 17 in its upper surface which .allows the air to escape in an axial direction, but under reduced pressure.

:In this embodiment, the air exhausted trom the bearing 5 passes through the holes 11 into la circular chamber 18 due to the tact that the holes 11 :are offset circumferentially with respect to the slotsl 17. 'Ilhe air stream is broken up by virtue of its passage through chambers 10 and 18, whereby its original force is -further reduced so that it will no longer produce an objectionable jet when it leaves through the axial openings 17. v

. The :air exhausted from the turbine through the diront bearing 4 is discharged into the atmosphere through the annular recess 19 .an-d the annular clearance space 20 .Patented Aug. l27, 1963 However, the

between the rotor shaft 3 and the front wall 7. Although the air exhaust `at' the front end of the head is not usually disturbing, the arrangement according to the present inventlon is an improvement over lthe previous arrangement of a series'of air holes in that a much more uniform exhaust is provided by utilization of `the annular clearance space 20.

Another improvement in the present invention is exemplified by the fact that the front chamber Wall `7 is provided with .an interior circular chamber 21 Which is in communication with the water-conveying tube 22. The front wall of the casing is also provided with one or more dis-charge openings 23 through Which lthe Water may discharge from the chamber 21 into the `atmosphere Ias shown ing means to position .the 4turbine means within the housing means, said handle means being provided with means to supply Kgaseous fluid to the interior of the housing means, said rear wall being provided with annular chamber means, said-rear wall being provided with an opening in communication with said annular chamberrmeans and the interior of the housing and also provided with an annular :opening in communication with the chamber means 'and the atmosphere, said frontV wall being provided with an opening in communication with the interior of the housing means and the atmosphere, and means to supply vcoolant -uid to ya tool positioned in said shaft means.

V2. The invention ,as dened in claim 1, wherein said rear wall is provided with an opening in alignment with said shaft means to receive an ejector tool.

3. The invention as defined in claim l, wherein one end of said shaft means is spaced `from the interior of said rear wali only an lamount sufficient to prevent frictional engagement therebetween.

4. The invention as defined in claim 1, wherein said opening in -the front kwall surrounds said shaft means and 1 is of larger diameter than theshaft'rneans to permit a portion of the gaseous fluid in the housing to escape therethrough.

5. The invention as defined in claim 1, wherein said front Wall is provided `with :an annularly ext-ending interiorly disposed chamber, and said means .to supply coolant fluid includes conduit means provided in said handle in `coinmunioation with said annular chamber and a plurality of openings provided in the frontfwal-l in communication with said yannular chamber;

6. The invention :as defined in claim 1', wherein said annular opening in communication with the chamber in the rear wall `and the atmosphere is positioned to direct exhausted fluid in an :axial direction, landj said opening in communicationy with saidchamber in the rear wall and the interior oi the housing is offset with respect to said annular opening. v y

7. The invention las defined in claim l, rwherein Said annular oharnberin the rear wall isdefined by a pair 'K axially spaced radially extending portions, the outermost of said porti-ons being generally disc-shaped :and overlying said opening in .the rear Wall in communication v,with the interior of the housing.

8. The .invention as deiined in yclaim 7, wherein said pair of axially spaced portions .are integrally `formed.

'References Cited in the le of. this patent UNITED STATSPATENTS 2,180,993 Monnier Nov. 2l, 1939 v FOREIGN PATENTS 43,927' Denmark Mar. 30, 1931 

1. IN HIGH SPEED CONTRA-ANGLE DENTAL HANDPIECES, THE COMBINATION INCLUDING, HANDLE MEANS, CYLINDRICAL HOUSING MEANS HAVING FRONT AND REAR END WALLS SECURED TO ONE END OF THE HANDLE MEANS, GASEOUS FLUID-DRIVEN TURBINE MEANS HAVING HOLLOW SHAFT MEANS TO REMOVABLY RECEIVE A TOOL THEREIN, GASEOUS FLUID-LUBRICATED ANTI-FRICTION BEARING MEANS TO POSITION THE TURBINE MEANS WITHIN THE HOUSING MEANS, SAID HANDLE MEANS BEING PROVIDED WITH MEANS TO SUPPLY GASEOUS FLUID TO THE INTERIOR OF THE HOUSING MEANS, SAID REAR WALL BEING PROVIDED WITH ANNULAR CHAM- 